Generally a carrying case for a device such as a portable electronic instrument comprises an upper and lower module which are hinged together. For example a briefcase type field testing device might contain electronic circuitry in both the upper and lower module, and upon unfolding the control panels of both modules are exposed. Because the device is unfolded and subsequently folded along an axis, simple hinges will suffice with a latching mechanism secured to the edge opposite to the hinged edge. However if it is necessary upon unfolding the case to move apart the modules a limited distance while maintaining their relative alignment as shown in FIGS. 1A and 1B the common scissor link assembly will not suffice.
Although the scissor link assembly can maintain alignment while extended (FIGS. 2T and 2S) and permits retraction (FIGS. 3T and 3S), upon folding and latching the scissor link assembly is still free to extend (FIGS. 4S and 4E). Unless a latch is also placed at the edge of the case upon which the scissor is secured the case can open (FIGS. 5S and 5E), separating the modules and placing a high stress on the latch at the opposite edge of the case. Even if such a secondary latch is provided, the operator, by inadvertently failing to secure the auxiliary latch, can still expose the device to damage. Such an eventuality is obviously undesirable, particular for valuable instruments.